Vehicles currently include various systems whose operation depends on the occupancy of the vehicle. For example, it has been known for some time that an occupant restraint or protection device can be designed to deploy differently depending on the type of occupants to be protected by the device (see for example, U.S. Pat. No. 5,829,782 (Breed et al.)). A classification of the occupancy of the vehicle is therefore desired in order to optimize the deployment of the occupant protection device.
Moreover, it is known that the position of the occupant can also affect the operation of various systems in the vehicle, most importantly, the occupant protection device (see, for example, U.S. Pat. No. 5,653,462 (Breed et al.)). Determination of the position of the occupant is therefore desired to optimize the deployment of the occupant protection device.
Lichtinger et al. (U.S. Pat. No. 6,636,792) describe a method for controlling output of a classification algorithm having two stages, a track stage and a lock stage. In the track stage, the occupant is repeatedly classified and whatever classification is obtained is output. The track stage continues until a predetermined number of consistent and consecutive classifications are observed, at which time, that classification is locked and considered the current classification, i.e., the algorithm reaches the lock stage. During the track stage however, whenever a classification is obtained which is different from the immediately preceding classification, the count of the number of consistent and consecutive classifications also begins anew. Thus, if the number of classifications needed to lock is 20 and the same classification of an adult is returned for 15 consecutive times, and then a single different classification is obtained, the process would remain in the track stage and the process of counting consistent and consecutive classifications begun anew. The output classification during the track stage would thus be whatever the immediately obtained classification is without regard to any previous classification. This continues as long as the classification has not been returned the predetermined number of times to reach the lock stage. Occupant classification is not likely optimal in Lichtinger et al. because it discloses changing the current or output classification based only on a change between consecutive classifications (in the track stage) or relative to a pre-determined threshold (in the lock stage). During the lock stage, the threshold is invariable.
What is needed therefore is an algorithm which can optimize both the classification of the occupancy of the vehicle and the determination of the position of the occupants.